3TB Drive but Can Only Use 2TB – You Can Fix It Quickly

You may find a 3TB drive is only showing 2TB in Computer or Windows Explorer. Or in other words, you can only use 2TB space even if the disk is 3TB or larger. Below is an example I picked out from the internet:

Recently, I bought a 3TB SATA drive and plan to use it as a data disk. However, in Disk Management the new drive appears as one 2TB partition with a 746GB unallocated space where I can’t do any operation even creating partition. Why I can only use 2TB space from a 3TB hard disk? Below is a screenshot of this disk in Disk Management.

It is believed that people who are troubled by this issue or similar issues would want to know why this happens and how to use all 3TB storage space.

Why We Can Only Use 2TB Space from a 3TB Hard Disk

This happens mostly because your hard disk was initialized to MBR. The organization of MBR partition table limits the maximum addressable storage space of a disk to 232 × 512 bytes ≈ 2TB if the disk is employing 512 bytes sector. Therefore, you can only use 2TB space even if the disk is 3TB or larger, and the remaining space is shown as unallocated space where you can do nothing. Since unallocated space will not appear in My Computer, a 3TB hard disk only shows 2 TB there if it is initialized to MBR.

Tip: if the disk is using 4K native sector, the maximum addressable storage space is 16TB. To check what type of sector your hard disk using, you can use the “Show Disk Properties” feature of MiniTool Partition Wizard.

Under this case, if you want to use all 3TB space, the best choice is to convert MBR to GPT, because GUID Partition Table supports a very large disk or partition size. Then, let’s see how to complete the conversion without losing data.

How to Convert an MBR Disk to GPT Disk

Both Windows built-in Disk Management utility and Diskpart allow users to convert an MBR disk to GPT, but they work only when there is no partition on the disk. If no files are saved, you can delete all partitions via the Delete Volume feature. But what if crucial data have been stored? Backup all important data, then delete those partitions, and convert the MBR disk to GPT? Undoubtedly, it’s not a wise choice.

Actually, there is a better method:

Convert MBR disk to GPT by using MiniTool Partition Wizard which can help you complete the conversion without deleting any partition. More importantly, it’s a freeware if you are running it on Windows XP, Windows 7, Windows 8, Windows 10, or other Windows non-server operating systems. But it should be NOTED that Partition Wizard 9.1 can only convert a data disk to GPT. If you want to convert a system disk to GPT, you’ll need to use the latest version which will be released in few days, and this version could keep your Windows bootable after conversion, if UEFI boot is supported and enabled by your computer. You can follow MiniTool in Google+ or Facebook to get the newest product information.

Then, let’s see how to change an MBR disk to GPT by using MiniTool Partition Wizard.

Firstly, launch the program to get its main interface after successful installation.

Then, right click the 3TB MBR disk and choose “Convert MBR Disk to GPT Disk” feature from the popup menu.

Now, we can preview the selected MBR disk is converted to GPT, but this is only a preview effect. Therefore, please click “Apply” button on the top left corner to apply this change.

Once the application is done, you can create a new partition using the 746GB unallocated space, or add the unallocated space to existing partitions via the function “Move/Resize Partition” or “Extend Partition” feature of Partition Wizard.

Further Reading:

Sometimes you may find a 3TB hard disk only shows 746GB, which is largely because you are still using an old version of Intel® Rapid Storage Technology driver, and the solution is to update the driver to the latest version. For more details, please see the post How to Fix: New 3TB Drive Only Shows 746GB.

There is another big limit in MBR partitioning scheme: users can only create the maximum number of 4 primary partitions on an MBR disk. However, on a GPT disk, you can create up to 128 partitions which could function like primary partitions on MBR disk. Therefore, when you want to create more primary partitions, just convert the MBR disk to GPT.

Is your 3TB or larger hard disk only showing up 2TB in Computer? Now, convert it to GPT by using the recommended freeware so as to use all its space.